Where can I find a full and comprehensive knowledge about all nodes?
A good source of all the nodes is Blender manual:


Compositing nodes
Cycles material nodes
Blender Internal material nodes


There are also examples of usage, which is most important when it comes to nodes. What matters is the whole network, not just how individual nodes work.

Some other sources:


the Cycles shader encyclopedia - just shader nodes examples
Chocofur shader examples - full material examples
Shader Forge - collection of paid and free shader breakdowns
PBR by CynicatPro - pbr material breakdowns covered also by BlenderGuru here and here.


Some non-bundled addon nodes:


Animation nodes
Sverchok nodes
LuxRender nodes


For the complete Blender resources database head over here.